U.S. Pat. No. 6,193,451 discloses a tool coupling having a first coupling part having a conical pin, and a second coupling part that has a conical seat. The conical pin of the first coupling part is insertable into the conical seat of the second coupling part, and from an inserted position, the first coupling part can be clamped in the conical seat by means of a pull member, which acts on a number of segments that, when the pull member is retracted, are displaced outward and engage a circumferential recess of a cavity of the conical pin. In that connection, the conical pin is pulled into the conical seat so that a support surface of the first coupling part lies flat against a corresponding support surface of the second coupling part in a plane perpendicular to the center axis of the coupling parts. This tool coupling works very well and is used in many different machine tools. Because the pull member presses the walls of the conical pin outward at the same time as the support surfaces abut against each other, a very rigid clamping of the first coupling part in an exact and predetermined positioning is obtained.
A disadvantage of this solution is, however, that the tool coupling contains many movable parts in the interface between the first coupling part and the second coupling part. Therefore, the tool coupling becomes sensitive to dirt and particles that may enter particularly into the area of the segments and contribute to the tool coupling seizing or in the worst case interconnecting the coupling parts in a less exact position. In addition, in small dimensions of the tool coupling, the manufacture of the individual parts and the handling and the mounting of the tool coupling with the many parts included are complicated.
SE-303658 offers a possible solution to these complex problems and discloses a kind of bayonet coupling that allows replacement of the segments of the tool coupling according to U.S. Pat. No. 6,193,451 by a pull member that, together with the first coupling part in the cavity of the conical pin, forms a bayonet coupling. The tool coupling that is shown in SE-303658 is, however, less exact and should, therefore, not able to guarantee any exact positioning of the first coupling part in relation to the second coupling part, neither in the axial direction nor in a circumferential direction.
The present disclosure recognizes such, by the fact that the first coupling part is turned in relation to the pull member, there arises an uncertainty about the final position of the first coupling part in the circumferential direction. Further, no specific abutment in the axial direction is demonstrated, which means that the axial position of the first coupling part is not exactly defined.